Can end closure curl

ABSTRACT

A continuous curl formed on the periphery of a can end component prior to the first and second operations of double seaming the can end component to an end of a can body has an inner annular portion of a configuration substantially that of a surface of revolution generated by three successive merging arcs including an inner arc struck by a first radius R1, a middle arc struck by a second radius R2, and an outer arc struck by a third radius R3, where R1&gt; R2&gt; R3, and an outer annular portion of a configuration substantially that of a generally planar surface which is parallel to a plane formed by the innermost marginal edge of the inner arc of the inner annular portion of the continuous curl. A curler tool for forming the continuous curl has a curl-forming groove which has a contour substantially the same as the configuration of the inner and outer annular portions of the continuous curl formed by the curler tool.

United StatesPatent 1 Gedde [541 CAN END CLOSURE CURL Erik Gedde, ParkRidge, 111.

[73] Assignee: American Can Company, Greenwich, Conn.

[22] Filed: June 11, 1971 [21] Appl.No.: 152,066

[75] Inventor:

[52] US. Cl. ..220/67, 113/121 C Brooksonl. ...1l3/l2l C Baker ..220/67Primary Examiner-Joseph R. Leclair AssistantExaminer-James R. GarrettAtt0mey-Robert P. Auber, George P Ziehmer,

Leonard R. Kohan and John R. Flanagan Feb. 6, 1973 [57] ABSTRACT AContinuous curl formed on the periphery of a can end component prior tothe first and second operations of double seaming the can end componentto an end of a can body has an inner annular portion of a configurationsubstantially that of a surface of revolution generated by threesuccessive merging arcs including an inner arc struck by a first radiusR, a mid clle arc struck by a second radius R and an outer arc struck bya third radius R where R R R and an outer annular portion of aconfiguration substantially that of a generally planar surface which isparallel to a plane formed by the innermost marginal edge of the innerarc of the inner annular portion of the continu ous curl. A curler toolfor forming the continuous curl.

6 Claims, 4 Drawing Figures INVENTOR.

' [A /K 652.05 BY CAN END CLOSURE CURL BACKGROUND OF THE INVENTION Thepresent invention relates generally to improved double seams and moreparticularly to a continuous curl formed on the periphery of a can endclosure and a curler tool for making the same which allows forsubsequent improved double seam formation.

In attempting to form double seams between a can body and aconventionally configured end closure formed of lightweight sheet metalof relatively high hardness, such as 80 pound to 95 pound DR9 tinplate,it has been found that deformities such as wrinkles are formed in thecover hook of the closure flange by the first operation double seamingroll concurrently as the roll forms the cover hook. These wrinkles notonly result in unsightly double seams, but also break the continuity ofthe double seam and in some instances even result in perforation of thecan body during the double seaming operations, and thus often preventthe formation of a tight hermetic seal between the can end closure andthe can body.

Prior to this time, the curler tool which was used to form the curl onthe end closure prior to the first and second operations double seaming,had a curl-forming groove with a single radiused contour, commonlywithin the range of from approximately 0.038 inch to 0.042 inchnwhen theouter marginal portion of this curl was subsequently reformed upwardsinto a cover hook feature during the first operation double seaming,wrinkles formed on the cover hook feature which subsequently adverselyaffected the formation of the double seam and the quality of the sealbetween the end closure and the can body as has been describedhereinbefore.

This problem of wrinkle formation on the cover hook feature during thefirst operation double seaming has been greatly reduced or eliminated bythe present invention. The curler tool of the present invention has acurl-forming groove of a particular contour which provides for thepreforming of the cover hook feature on the curl in the curler operationprior to the first operation double seaming to thereby permit areduction in the curl reforming work subsequently required in the firstoperation double seaming. This work reduction greatly reduces oreliminates the magnitude of the wrinkles formed on the cover hookfeature during the first operation double seaming and results in animproved double seam. The continuous curl of the present invention,being formed by the curler tool, has a configuration substantially thesame as the contour of the curler tool groove which forms the curl.

SUMMARY OF THE INVENTION A continuous curl formed on the periphery of acan end component prior to the first and second operations of doubleseaming the can end component to an end of a can body has an innerannular portion ofa configuration substantially that of a surface ofrevolution generated by three successive merging arcs including an innerarc struck by a first radius R a middle are struck by a second radius Rand an outer arc struck by a third radius R;,, where R R R and an outerannular portion of a configuration substantially that of a generallyplanar surface which is parallel to a plane formed by the innermostmarginal edge of the inner are of the inner annular portion of thecontinuous curl. A

curler tool for forming the continuous curl has a curlforming groove ofa contour substantially the same as the configuration of the inner andouter annular por- 5 tions of the continuous curl formed by the curlertool.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary sectional viewof a can end closure as initially die-formed before being curled by thecurler tool of the present invention;

FIG. 2 is an enlarged fragmentary sectional view of the can end closureof FIG. 1 and of the curler tool of the present invention showing theperipheral flange of the end closure aligned with the curler tool beforethe curl-forming operation;

FIG. 3 is an enlarged fragmentary sectional view of the end closure ofFIG. 1 and of the curler tool showing the continuous curl of the presentinvention formed in the tool after the curl-forming operation; and

FIG. 4 is a fragmentary sectional view of the end closure of FIG. 1showing the continuous curl of the present invention formed on theperiphery of the end closure.

25 DETAILED DESCRIPTION OF THE INVENTION In FIG. I there is illustrateda fragmentary section of a circular tinplate can end closure, generallydesignated 10, as initially die-formed before being curled by a curlertool, generally designated 12 (FIG. 2).

The end closure generally comprises a flat countersunk central panel 14which merges at its outer end with a generally upwardly extendingcountersink wall 16 which in turn merges at its upper end with agenerally outwardly extending, curved, annular flange 18.

Referring now to FIG. 2, the annular flange 18 of the end closure 10 isshown aligned with a curl-forming groove, generally designated 20,formed in a body 22 of the curler tool 12.

The curl-forming groove is defined by an inner surface 24 and an outersurface 26.

The inner surface 24 has a contour substantially that of a surface ofrevolution generated by three successive merging arcs. The first of thethree successive arcs, defining an inner surface section 28, is struckby a first radius R The first radius R strikes the first are by sweepingthrough a first angle 19 about a first center of curvature C The secondof the three successive arcs, defining a middle surface section 30, isstruck by a second radius R The second radius R strikes the second areby sweeping through a second angle 6 about a second center of curvatureC with the second center C being located along the first radius R at theend of its sweep through the first angle 0,. The third of the threesuccessive arcs, defining an outer surface section 32, is struck by athird radius R The third radius R strikes the third are by sweepingthrough a third angle 0 about a third center of curvature C with thethird center C being located along the second radius R, at the end ofitssweep through the second angle 0 In the preferred embodiment of thecurler tool 12, the first radius R is approximately equal to 0.166 inchand the first angle 0 is approximately equal to 20, the second radius R,is approximately equal to 0.050 inch and the second angle (9 isapproximately equal to 80, and the third radius R is approximately equalto 0.025 inch and the third angle is approximately equal to 75.

The outer surface 26 of the curl-forming groove has a contoursubstantially that of a generally planar surface which is in a plane P,substantially parallel to a plane I formed by the innermost marginaledge 34 of the inner surface section 28 of the inner surface 24 of thecurl-forming groove 20.

Prior to the curl-forming operation, as shown in FIG. 2, the marginaledges 36, 38 of an outer portion 40 of the peripheral annular flange 18,which portion 40 will be formed into a continuous curl 42 by the curlertool 12, are brought into contact with the surfaces 44, 46 of the curlertool 12, the surfaces 44, 46 being exterior respectively to the innerand outer surfaces 24, 26 of the curl-forming groove 20. In thecurl-forming operation, the outer portion 40 is moved toward thecurlforming groove 20 which causes the reforming or molding of the outerportion 40 into the configuration of the continuous curl 42 as shown inFIG. 3.

As shown in FIG. 3, the continuous curl 42 has a configuration which issubstantially the same as the contour of the inner and outer surfaces24, 26 of the curlforming groove 20 of the curler tool 12. The curl 42is comprised by an inner annular portion 48 and an outer annular portion50.

The inner annular portion 48 has a configuration substantially that of asurface of revolution generated by three successive merging arcs, wherethe surface of revolution is coincident with the exterior surface 52 ofthe inner annular portion 48. The first of the three successive arcs,defining the exterior surface of an inner section 54 of the innerannular portion 48, is struck by the first radius R,. The first radiusR, strikes the first are by sweeping through the first angle 0,, aboutthe first center of curvature C,. The second of the three successivearcs, defining the exterior surface of the middle section 56 of theinner annular portion 48, is struck by the second radius R The secondradius R strikes the second arc by sweeping through the second angle 0about the second center of curvature C with the second center C beinglocated along the first radius R, at the end of its sweep through thefirst angle 6,. The third of the three successive arcs, defining theexterior surface of an outer section 58 of the inner annular portion 48,is struck by the third radius R,,. The third radius R,, strikes thethird are by sweeping through the third angle 0,, about the third centerof curvature C with the third center C being located along the secondradius R, at the end of its sweep through the second angle 6 Thepreferred lengths of the radii R,, R and R and degrees of the angles 0,,9 and 0 are the same with regard to the continuous curl 42 as thosegiven with regard to the curler tool 12.

The exterior surface of the outer annular portion 50 of the continuouscurl 42 has a configuration substantially that of a generally planarsurface which is in the plane P, substantially parallel to the plane Pformed by the exterior surface of the innermost edge 60 of the innersection 54 of the inner annular portion 48 of the curl 42.

In FIG. 4 there IS illustrated a fragmentary section of the end closure10 with the continuous curl 42 being formed on the periphery thereof.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description and it will beapparent that various changes may be made in the form, construction andscope ofthe invention without sacrificing all of its materialadvantages, the form hereinbefore described being merely a preferredembodiment thereof.

I claim:

1. A continuous curl formed on the periphery of a can end componentprior to the first and second operations of double seaming said can endcomponent to an end of a can body, comprising:

an inner annular portion of a configuration substantially that of asurface of revolution generated by three successive merging arcsincluding an inner arc struck by a first radius R,, a middle are struckby a second radius R,, and an outer arc struck by a third radius R,,where R, R R and an outer portion of a configuration substantially thatof an annular generally planar surface which is parallel to a planeformed by the innermost marginal edge of said inner are.

2. A continuous curl according to claim 1 wherein R, is approximatelyequal to 3R and approximately equal t0 6R3.

3. A continuous curl according to claim 1 wherein R, approximatelyequals 0.166 inch, R approximately equals 0.050 inch, and Rapproximately equals 0.025 inch.

4. A can end component for double seaming to an end of a can body,comprising:

a can end defining portion; and

an integral peripheral flange, said flange being annular in outline andhaving an outer portion in the form of a continuous curl, said curlhaving an inner section of a configurationsubstantially that of asurface of revolution generated by three successive merging arcsincluding an inner arc struck by a first radius R,, a middle arc struckby a second radius R,, and an outer arc struck by a third radius R,,,where R, R R and an outer section of a configuration substantially thatof an annular generally planar surface which is in a plane substantiallyparallel to a plane formed by the innermost marginal edge of said innerarc.

5. A can end component according to claim 4 wherein R, is approximatelyequal to 3R and approximately equal to 6R 6. A can end componentaccording to claim 4 wherein .R, approximately equals 0.166 inch, Rapproximately equals 0.050 inch, and R approximately equals 0.025 inch.

1. A continuous curl formed on the periphery of a can end componentprior to the first and second operations of double seaming said can endcomponent to an end of a can body, comprising: an inner annular portionof a configuration substantially that of a surface of revolutiongenerated by three successive merging arcs including an inner arc struckby a first radius R1, a middle arc struck by a second radius R2, and anouter arc struck by a third radius R3, where R1 > R2 > R3; and an outerportion of a configuration substantially that of an annular generallyplanar surface which is parallel to a plane formed by the innermostmarginal edge of said inner arc.
 1. A continuous curl formed on theperiphery of a can end component prior to the first and secondoperations of double seaming said can end component to an end of a canbody, comprising: an inner annular portion of a configurationsubstantially that of a surface of revolution generated by threesuccessive merging arcs including an inner arc struck by a first radiusR1, a middle arc struck by a second radius R2, and an outer arc struckby a third radius R3, where R1 > R2 > R3; and an outer portion of aconfiguration substantially that of an annular generally planar surfacewhich is parallel to a plane formed by the innermost marginal edge ofsaid inner arc.
 2. A continuous curl according to claim 1 wherein R1 isapproximately equal to 3R2, and approximately equal to 6R3.
 3. Acontinuous curl according to claim 1 wherein R1 approximately equals0.166 inch, R2 approximately equals 0.050 inch, and R3 approximatelyequals 0.025 inch.
 4. A can end component for double seaming to an endof a can body, comprising: a can end defining portion; and an integralperipheral flange, said flange being annular in outline and having anouter portion in the form of a continuous curl, said curl having aninner section of a configuration substantially that of a surface ofrevolution generated by three successive merging arcs including an innerarc struck by a first radius R1, a middle arc struck by a second radiusR2, and an outer arc struck by a third radius R3, where R1 > R2 > R3,and an outer section of a configuration substantially that of an annulargenerally planar surface which is in a plane substantially parallel to aplane formed by the innermost marginal edge of said inner arc.
 5. A canend component according to claim 4 wherein R1 is approximately equal to3R2, and approximately equal to 6R3.